1. Field of the Invention
The present invention relates generally to clamp assemblies for connecting one member to a support member. In a particularly preferred aspect, the invention relates to an ultra high strength clamp assembly to attach a pipe or line, such as an umbilical line, to another pipe. In a specific embodiment, the invention is particularly adapted for use as a subsea clamp assembly to attach an umbilical line to a choke or kill line of a subsea riser. In the specific embodiment the invention is particularly adapted for use as a variable height stand-off assembly to attach an umbilical line to a choke or kill line in a marine riser assembly.
2. Background of the Invention
The need often arises for a clamp assembly to attach a cable, hose or pipe to a support member or pipe. The situation often occurs where an umbilical line is required to be secured to a support member or pipe at a certain distance away from the support member, for example, to accommodate insulation, floatation and mechanical barriers.
In the offshore drilling and production industry, it is frequently necessary to run umbilical lines hundreds and even thousands of feet below the support vessel or drilling or production platform down to the sea floor and beyond. Typically, the umbilical lines, which may include electric, MUX (fiber optics), and hydraulics, are required to be attached to a support member, such as a choke or kill line, or mud line on a subsea riser system. Due to the high cost of working in such environments, it is critical that the clamp assembly be reliable and dependable to firmly secure the clamped members to prevent costly consequences, such as loss of signal in a fiber optic cable due to slack in an umbilical line which can create a sharp radius in the line preventing signal transmission. Various types of clamp assemblies and stand-off assemblies have been used in these situations. The prior art clamp assemblies and stand-off assemblies have been very costly and time consuming to make, use and install, and many do not clamp the umbilical lines with enough force.
In one embodiment of the invention, there is provided a base clamp for a tubular member which forms a mounting base for another clamp or an extension leg. The clamp comprises a saddle structure and at least one U-bolt. The saddle structure has a first end, a second end, an upper surface and a lower surface. The lower surface defines a trough extending from the first end to the second end for mounting the saddle structure to a tubular member. The saddle structure further defines at least one pair of parallel apertures positioned one on each side of the trough for receiving a first U-bolt for fastening the saddle structure to the tubular member. A U-bolt having a first end and a second end is received by the apertures and extends over the trough. The upper surface of the saddle structure defines a track configured to receive a shoe.
The track can connect the base clamp via a support leg to a line clamp according to another embodiment of the invention for a tubular hose or cable. The line clamp comprises an upper clamp half, a lower clamp half, a hinge pin connecting the halves, a fastener latching the halves, and a support leg having a shoe. The upper clamp half has a downwardly facing parting line face. The lower clamp half has an upwardly facing parting line face and is positioned in a face to face relationship with the upper clamp half so that the parting line faces are side by side. The hinge pin pivotally connects the clamp halves along a hinge edge. A fastener connects the clamp halves along a latch edge. The support leg extends from the lower clamp half and has an upper end attached to the lower clamp half and a lower end. The shoe is positioned on the lower end of the support leg.
Alternatively, the track can connect the base element to an extension leg according to another embodiment of the invention which can be used to connect the base clamp to the line clamp, or, if desired, to another extension leg. The extension leg has a first end and a second end and a longitudinal axis extending between the first end and the second end. A shoe is positioned on the first end of the extension leg. A track is positioned on the second end of the extension leg which is configured to receive the shoe.
Preferably, the line clamp employs an elastomeric liner according to another embodiment of the invention to reliably position the clamped line. The elastomeric liner is provided in two halves. Each liner half is formed from an elastomeric material and has an outside wall and an inside wall which defines at least one semi-cylindrical trough. The trough has a longitudinal axis, a first end, and a second end and is sized for closely receiving a hose or cable to be clamped. The outside wall is configured to be to be closely received by an inside surface of a clamp half.